Blade for cutting wallboard

Abstract

A blade having a chisel point at one end and a cutting point intermediate its ends is mounted in the blade holder of a sabre saw. As the sabre saw is moved along the wallboard to be cut, the chisel point on each stroke moves through the gypsum core, its rearwardly inclined end forcing the gypsum back into the kerf. The chisel point need only fracture the paper on the rough side of the wallboard, although it may pass completely therethrough. The cutting point severs the paper on the finished side of the wallboard.

I claim: 
     
       1. A blade for cutting comprising an elongated flat body having smooth first and second ends, smooth first and second spaced edges plus a smooth third edge at said first end extending toward said second end and to said second edge, said first edge having a first portion thereof extending from said third edge toward said second end and toward said second edge to form a chisel point at said first end, the sides of said body being generally parallel at said second end and said first and third edges being blunt or flat between said generally parallel sides. 
     
     
       2. A blade in accordance with claim 1 in which said first edge has a second portion forming a continuation of said first portion, which extends toward said second end and away from said second edge. 
     
     
       3. A blade in accordance with claim 2 in which said first edge has a third portion forming a continuation of said second portion, said third portion being straight and parallel to a first portion of said second edge. 
     
     
       4. A blade in accordance with claim 3 in which said blade has a longitudinal axis along which it is intended to be reciprocated, the tip of said chisel point being nearer said longitudinal axis than is said third edge portion. 
     
     
       5. A blade in accordance with claim 4 in which the juncture of said first and second edge portions of said first edge is nearer said axis than the tip of said chisel point. 
     
     
       6. A blade in accordance with claim 5 in which said first portion of said second edge extends from said third edge a greater distance than the sum of said first and second portions of said first edge. 
     
     
       7. A blade in accordance with claim 6 in which said second edge has second and third portions, said second portion of said second edge extending toward said second end and away from the third portion of said first edge. 
     
     
       8. A blade in accordance with claim 7 in which the third portion of said second edge extends from the second portion of said second edge toward said second end in a parallel relation to the third portion of said first edge. 
     
     
       9. A blade in accordance with claim 2 in which the first portion of said first edge is straight and the second portion thereof is curved. 
     
     
       10. A blade in accordance with claim 1 in which the distance between said first and second edges is less at said first end than at said second end. 
     
     
       11. The combination with a sabre saw including a reciprocal blade holder, an elongated blade comprising an end portion held by said holder and a cutting end portion having a chisel point, said cutting end portion being formed by a smooth forward edge and smooth end edge, said forward and end edges extending at an acute angle with respect to each other and being blunt or flat from one side of said cutting end portion to the other side thereof to form said chisel point. 
     
     
       12. The combination set forth in claim 11 in which said forward edge curves forwardly after forming said chisel point and then extends in a straight line, the curved and straight portions of said forward edge forming an obtuse angle and thus a cutting point spaced from said chisel point. 
     
     
       13. The combination set forth in claim 12 in which the tip of said chisel point is disposed slightly rearwardly of said cutting point. 
     
     
       14. The combination set forth in claim 13 in which the stroke of said reciprocal blade holder is less than the thickness of the wallboard to be cut and said cutting point is spaced from said chisel point a distance less than the thickness of said wallboard.